Sealing system

ABSTRACT

A sealing system, in particular for sealing multi-part exhaust gas pipes for an internal combustion engine, with at least a first flange part ( 9 ) and a second flange part ( 11 ) that guide a heat flow ( 5 ) and that border between them a receiving space ( 33 ) for at least one sealing element ( 29, 31 ), is characterized in that the flange parts ( 9, 11 ) that are adjacent to one another in each case form a ring flange ( 13 ) that extends outward, facing away from the heat flow ( 5 ) and running transversely to the latter, in which the faces ( 15, 17 ) of the flange parts ( 9, 11 ) that are adjacent to one another form a chamber to some extent of the receiving space ( 33 ) of the sealing element ( 29, 31 ).

The invention relates to a sealing system, in particular for sealing multi-part exhaust gas pipes for an internal combustion engine, with at least first and second flange parts that guide a heat flow and that border between them a receiving space for at least one sealing element.

Sealing systems of this type are known. DE 10 2004 060 845 A1 shows, for example, such a sealing system for the exhaust gas pipe of a reciprocating engine, as a sealing element, a metal sealing ring in the form of a profile element with a C-shaped profile cross-section being provided. Sealing elements in the exhaust gas system are subject to very high temperatures, which can exceed 600° Celsius. Even though materials with properties that are selected for heat resistance are used, the sealing elements lose their functional properties required for sealing in cases where high operating temperatures prevail; the elasticity of the sealing elements is reduced in particular by creep processes caused by excessively high thermal stresses.

In this context, the object of the invention is to make available a sealing system that ensures reliable sealing when used in the hot gas range, even when high temperatures occur in the exhaust gas pipes that are to be sealed.

According to the invention, this object is achieved by a sealing system that has the features of claim 1 in its entirety.

Accordingly, an essential characteristic of the invention consists in that the flange parts that are to seal against one another form a ring flange that faces away from the heat flow and extends outward transversely to the latter, in which the receiving space for the sealing element is designed for the respective sealing element such that a chamber is formed for the sealing element. Such an installation of the sealing element in a ring flange that extends outward away from the heat flow makes possible a thermal shield against the heat flow that is adequate for the operability and service life of the sealing element, such that the system according to the invention can also be used reliably on exhaust gas pipes that are subject to high thermal loads.

An especially effective thermal decoupling of the sealing element relative to the heat flow is produced when the receiving space, relative to the heat flow, is located on the radial outer end area of the flange parts, i.e., in the area of the flange that has the lowest temperature level.

In this connection, in the case of advantageous embodiments, the arrangement can be made such that the receiving space that is open radially outward is limited by a ring-shaped recess, which is created in at least one of the flange parts of its peripheral edge and is open on the face, as well as by the adjacent face of the other flange part. The thus formed receiving space for the sealing element is open on the peripheral side on the ring flange and thus forms only a partial chamber for the sealing element, such that on the radial outer side of the sealing element, no heat transfer to the latter takes place.

In additional especially advantageous embodiments, the arrangement is made such that the receiving space that is open radially outward is bordered axially by the adjacent faces of the flange parts and radially inward by an insertion element that is found between the flange parts. In this connection, the insertion element can act as a heat barrier between the inner heat flow and the receiving space of the sealing element, for example by the insertion element being formed by a metal fire ring, or, as an especially advantageous embodiment, by an insertion element that is made of a material of low heat conductivity, for example a non-metallic material, being provided.

As an alternative, the receiving space can also be formed by a flange part, which has an open, axially recessed annular groove on the face.

In an especially advantageous way, in the case of such configurations as additional heat protection for the sealing element, a cover element that is arranged in the annular groove and that forms a heat shield for the respective sealing element at least on its side that faces the face of the flange part can be provided.

As such a cover element, a metal ring element can be provided, for example a flat ring that is inserted between the sealing element and face of the flange part, or a ring element that has a curved or angled profile, which surrounds the sealing element not only on its side facing the face.

Preferably, a mold seal, which can have in particular a V- or C-shaped profile cross-section, is provided as a sealing element, the mold seal being preferably installed in the receiving space such that the C-profile is open radially inward. There also exists the possibility of providing to the sealing element, instead of a V- or C-shaped profile cross-section, a meandering profile cross-section like a bellows solution, in which several superjacent folds on top of each other form the cross-section.

As an alternative, metal crimping seals can be installed in the receiving space. In any case, the invention ensures thermal protection for the respective sealing element such that with metal sealing elements made from a material that is available for high-temperature use, a reliable sealing into the hot gas ranges is ensured. The ring shape for the sealing element can be circular or approximately ringlike. Also, ring shapes that are conceivable as ovals or rectangles, preferably with rounded corner areas. An annular groove that can be identified then preferably is to follow the respective ring shape of the sealing element.

Below, the invention will be explained in detail based on the embodiments that are depicted in the drawing. Here:

FIG. 1 shows, greatly simplified diagrammatically, a cutaway and half-page longitudinal section of adjacent pipe pieces of an exhaust gas pipe, the pipe pieces being mutually sealed by a sealing system according to an embodiment of the invention;

FIGS. 2 and 3 show longitudinal sections, similar to FIG. 1, of a second or third embodiment of the sealing system;

FIG. 4 shows a half-page longitudinal section of only the joint area of the adjacent flange parts of two pipe pieces, provided with a fourth embodiment of the sealing system, and

FIGS. 5 and 6 show similar depictions, provided with a fifth or sixth embodiment of the sealing system.

In the FIGS., a first pipe piece and a second pipe piece of an exhaust gas pipe are referred to as 1 or as 3. During operation of the respective internal combustion engine, the exhaust gas pipe of an exhaust gas heat flow 5 with a corresponding high exhaust gas temperature results. The pipe pieces 1 and 3 that are to be connected to one another and that are to seal against one another by means of the sealing system according to the invention in each case have a flange part 9 or 11 that projects radially outward relative to the pipe axis 7. The flange parts 9 and 11 together form a ring flange 13, the flange parts 9 and 11 having faces 15 or 17 that face one another. To connect the pipe pieces 1 and 3 to one another, the flange parts 9, 11 of the ring flange 13 are clamped to one another by suitable tensioning means, of which only tensioning means of the usual type in FIGS. 1 and 2 are indicated heavily schematized, in FIG. 1, tension rings 19 with threaded joints 21 being shown, and in FIG. 2, a tension ring 27 accommodated on bevelings 25 of the flange parts 9 and 11 being shown.

For the seal between the flange parts 9 and 11, FIG. 1 shows a two-layer metal crimping seal 29, while in the examples of FIGS. 2 to 6 in each case, a metal mold seal 31 of a C-shaped profile cross-section is shown. In each instance, the respective sealing element is chambered to some extent in a receiving space 33 that is formed between the flange parts 9 and 11. In the example of FIG. 1, the receiving space, which is open on the outer peripheral side on ring flange 13, is bordered axially by the faces 15 and 17 of the flange parts 9 or 11 and is bordered radially inside by an insertion element, in which the example of FIG. 1 is a metal fire ring 35, which is inserted between the flange parts 9 and 11 and borders the receiving space 33 with its radial outer annular edge 37.

Apart from the other tensioning means (tension ring 27), however, the example of FIG. 2 differs mainly in the respect that instead of the crimping seal 29, a mold seal 31 is installed in the receiving space 33 and that instead of the fire ring 35, a non-metallic insertion element is inserted between the flange parts 9 and 11, specifically a ring element 39 that is made of a material of poor heat conductivity. As materials for this purpose, for example, i.a., ceramic fiber materials, for example made of amorphous aluminum silicate fibers or crystalline aluminum oxide fibers, are suitable or any materials that form an effective heat shield between heat flow 5 and receiving space 33. The insertion element can also consist of a modern composite material, for example, can be formed from metallic or non-metallic material, which in the corresponding compound ensures a good heat shield.

FIG. 3 shows an embodiment in which the receiving space 33 is formed by a ring-shaped recess 41, which is created in the flange part 9 of its peripheral edge 43 such that the receiving space 33 is bordered axially by the face 17 of the flange part 11 and the opposite wall of the recess in the flange part 9. Analogous to the examples of FIGS. 1 and 2, the sealing element is thus accommodated in a receiving space 33 and partially chambered, the receiving space 33 in turn being located on the end of the ring flange 13 that is furthest out in the radial direction, i.e., in the range that has the lowest operating temperature. In modifying the embodiment according to FIG. 3, the receiving space 33 can also be formed by two ring-shaped recesses that face one another, which are created in each case in the flange part 9 as well as 11 of its peripheral edge, such that then the sealing element is arranged in approximately the middle with its C-shaped opening edge along the face between the two flange parts 9 and 11.

FIGS. 4 to 6 show embodiments in which the receiving space 33 in each case is formed by an annular groove 45, which is created recessed in axial direction in the flange part 11 of its face 17, whereby in connection with the face 15 of the flange part 9, a closed chamber for the mold seal 31 is formed.

In the examples of FIGS. 4 to 6, as an additional heat protection for the mold seal 31 that is located in the receiving space 33, in each case a cover element 47, which is inserted into the annular groove 45, in the form of a metal ring element is provided. The example of FIG. 4 is a flat ring element, while as cover elements 47 in the examples of FIGS. 5 and 6, profile rings are provided, specifically a curved ring in FIG. 5 and an angled ring in the example of FIG. 6. In any case, the cover element 47 is installed in the annular groove 45 such that the mold seal 31 is covered at least on the side that is facing the point of impact between the faces 15 and 17 of the flange part 9 or 11. As indicated in FIG. 4 by a flow arrow 49, the section of the point of impact between the faces 15 and 17 that is closest to the heat flow 5 is most heavily affected by the heat flow, against which that section of the cover element 47 facing the point of impact forms a shield. 

1. Sealing system, in particular for sealing multi-part exhaust gas pipes for an internal combustion engine, with at least a first flange part (9) and a second flange part (11) that guide a heat flow (5) and that border between them a receiving space (33) for at least one sealing element (29, 31), characterized in that the flange parts (9, 11) that are adjacent to one another in each case form a ring flange (13) that extends outward, facing away from the heat flow (5) and running transversely to the latter, in which the faces (15, 17) of the flange parts (9, 11) that are adjacent to one another form a chamber to some extent of the receiving space (33) of the sealing element (29, 31).
 2. The sealing system according to claim 1, wherein the receiving space (33) is located in a radial outer end area of the flange parts (9, 11) relative to the heat flow (5).
 3. The sealing system according to claim 2, wherein the receiving space (33) that is open radially outward is bordered by a ring-shaped recess (41), which is created in at least one of the flange parts (9) of its peripheral edge (43) and is open on the face (15), as well as by the adjacent face (17) of the other flange part (11).
 4. The sealing system according to claim 2, wherein the receiving space (33) that is open radially outward is bordered axially by the adjacent faces (15, 17) of the flange parts (9, 11) and radially inward by an insertion element (35, 39) that is located between the flange parts (9, 11).
 5. The sealing system according to claim 4, wherein an insertion element (39) that consists of a material of low heat conductivity is provided.
 6. The sealing system according to claim 1, wherein the receiving space (33) is formed by at least one flange part (11), which has an open, axially recessed annular groove (45) on the face (17).
 7. The sealing system according to claim 6, wherein at least one cover element (47), which forms a heat shield for at least one sealing element (31) at least on its side that faces the face (17) of the flange part (11), is arranged in the annular groove (45).
 8. The sealing system according to claim 7, wherein as a cover element, a ring element (47) with a flat, curved or angled profile is provided.
 9. The sealing system according to claim 8, wherein at least one mold seal (31) is provided as a sealing element.
 10. The sealing system according to claim 8, wherein at least one metal crimping seal (29) is provided as a sealing element. 